Merge branch 'main' into harpoon_port

Author: MinhPhan8803

docs/getting-started.md

@@ -105,7 +105,12 @@ The following output should be printed out:
 ## Troubleshooting
 
 ### Building dependencies:
-This step includes compiling the Linux kernel which can get quite resource intensive. In our tests `6GB` is the minimum value for which compiling Linux is possible, this means you might not be able to use Rex on machines with 6GB or less RAM. A sign that you ran into Out-Of-Memory (OOM) error is if you encounter this warning:
+
+This step includes compiling the Linux kernel which can get quite resource
+intensive. In our tests `6GB` is the minimum value for which compiling
+Linux is possible, this means you might not be able to use Rex on machines
+with 6GB or less RAM. A sign that you ran into Out-Of-Memory (OOM) error is
+if you encounter this warning:
 
 ```bash
 /root/rex/linux/scripts/link-vmlinux.sh: line 113: 55407 Killed                  LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
@@ -119,23 +124,65 @@ FAILED: load BTF from vmlinux: invalid argument
 
 Or similar problems.
 
-For WSL users, it is recommended to allocate more RAM to WSL before starting this step since WSL by default only utilizes half the RAM available on the host machine:
+For WSL users, it is recommended to allocate more RAM to WSL before
+starting this step since WSL by default only utilizes half the RAM
+available on the host machine:
+
+From a Powershell instance, create and open a `.wslconfig` file in your
+home directory:
 
-From a Powershell instance, create and open a `.wslconfig` file in your home directory:
 ```bash
 notepad $HOME/.wslconfig
 ```
 
 Add the following lines to the file then save:
+
 ```bash
 [wsl2]
-memory=6GB
+memory=8GB
+swap=8GB
 ```
 
 You should change the value to how much memory you want to allocate to WSL.
 
+Another issue that may happen is bootstrap failure due to the missing
+`libLLVM-19-rex.so`:
+
+```console
+  --- stderr
+  llvm-config: error: libLLVM-19-rex.so is missing
+  thread 'main' panicked at compiler/rustc_llvm/build.rs:264:16:
+  command did not execute successfully: "/home/chin39/Documents/rex-kernel/build/rust-build/x86_64-unknown-linux-gnu/llvm/bin/llvm-config" "--link-shared" "--libs" "--system-libs" "asmparser" "bitreader" "bitwriter" "coverage" "instrumentation" "ipo" "linker" "lto" "x86"
+  expected success, got: exit status: 1
+  stack backtrace:
+     0: rust_begin_unwind
+               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/panicking.rs:665:5
+     1: core::panicking::panic_fmt
+               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/core/src/panicking.rs:76:14
+     2: build_script_build::output
+     3: build_script_build::main
+     4: core::ops::function::FnOnce::call_once
+  note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
+Build completed unsuccessfully in 0:00:12
+FAILED: cargo rustc
+env 'RUSTFLAGS=-Z threads=8 -C target-cpu=native -C codegen-units=1 -C link-arg=-fuse-ld=mold -C link-arg=-Wl,-O1 -C link-arg=-Wl,--as-needed -C link-arg=-flto=thin' /usr/bin/python3 ../rust/x.py install --config=../rust/rex-config.toml --build-dir=./rust-build --set install.prefix=./rust-dist
+ninja: build stopped: subcommand failed.
+```
+
+Notably this may happen as a result of [`ba85ec815c2f ("rust: enable more
+optimizations and features in bootstrap
+config")`](https://github.com/rex-rs/rex/commit/ba85ec815c2fc9721e3b466d1c296bd7dd79b1b3),
+as it changes the linkage of `libLLVM` from static to dynamic, but rust
+bootstrap process does not rebuild `libLLVM.so` following the change.
+The issue can be fixed by removing the build directory created by meson and
+starting a clean build.
+
 ### Building the Rex samples:
-There are some caveats before you run this step. By default the `ninja` build tool uses a quite high level of parallelism, which might again cause OOM on personal machines. A sign of this happenning is if you try this step and run into similar errors to:
+
+There are some caveats before you run this step. By default the `ninja`
+build tool uses a quite high level of parallelism, which might again cause
+OOM on personal machines. A sign of this happenning is if you try this step
+and run into similar errors to:
 
 ```bash
 error: could not compile `core` (lib)
@@ -144,19 +191,24 @@ Caused by:
     process didn't exit successfully:
 ```
 
-To resolve this problem, try running with fewer commands in parallel using the `-j` argument, for example to run with 4 commands in parallel:
+To resolve this problem, try running with fewer commands in parallel using
+the `-j` argument, for example to run with 4 commands in parallel:
 
 ```bash
 meson compile -C build -j 4
 ```
 
-Our tests indicate a peak memory usage of 12GB with `-j 8`, so if you have less RAM it's helpful to keep the `-j` argument below 8.
+Our tests indicate a peak memory usage of 12GB with `-j 8`, so if you have
+less RAM it's helpful to keep the `-j` argument below 8.
 
 ### Booting the QEMU VM:
-By default our QEMU VM runs on 8GB of memory. To reduce this, open the qemu scripts using an editor and locate line 300:
+
+By default our QEMU VM runs on 8GB of memory. To reduce this, open the qemu
+scripts using an editor and locate line 300:
 
 ```bash
 MEMORY=8192
 ```
 
-And change this value to the number you want. Rex has been tested to work with 4GB or `MEMORY=4096`.
+And change this value to the number you want. Rex has been tested to work
+with 4GB or `MEMORY=4096`.

meson.build

@@ -73,3 +73,4 @@ sanity_test_scripts = join_paths(meson.project_source_root(), 'scripts/sanity_te
 runtest_deps = []
 
 subdir('samples')
+subdir('rex')

rex/meson.build

@@ -0,0 +1,30 @@
+build_dir = run_command(
+  realpath,
+  '--relative-to',
+  meson.current_source_dir(),
+  meson.current_build_dir(),
+  capture: true,
+  check: true
+).stdout().strip()
+
+env = environment()
+env.prepend('PATH', rust_bin)
+env.set('LINUX_OBJ', kbuild_dir)
+env.set('LINUX_SRC', join_paths(meson.project_source_root(), './linux'))
+env.set('CARGO_TARGET_DIR', join_paths(build_dir, 'target'))
+
+rex_build = custom_target(
+  'rex-build',
+  output: ['target'],
+  command: [
+    cargo_wrapper, rust_bin, '-Z',
+    'unstable-options',
+    '-C', meson.current_source_dir(),
+    'rustc', '-qr', '--',
+    '-Cenable_rex'
+  ],
+  env: env,
+  console: false,
+  build_always_stale: true,
+  build_by_default: false
+)